Doctors of Optometry Course Notes

Transcription

1 Doctors of Optometry Course Notes OD22 1 CE Contact Lens Management of the Irregular Cornea Monday, February 19, :05 am 10:00 am Plaza A 2 nd Fl Presenter: Dr. Maria Walker Dr. Maria K. Walker earned her Doctor of Optometry and Master of Vision Science degrees from The New England College of Optometry. She then completed a residency in Cornea & Contact Lenses at Pacific University. Dr. Walker currently teaches at the University of Houston College of Optometry, and is pursuing her PhD in scleral lenses. Her main interests include contact lens optics, corneal physiology, scleral contact lenses, and multifocal lens performance. Course Description This course is intended to provide practitioners with information on selection and management of specialty contact lenses for the irregular cornea. 1

2 Doctors of Optometry Course Notes NOTES: 2

3 Specialty Contact Lenses: Fitting the Irregular Cornea SPECIALTY CONTACT LENS OPTIONS IN 2018! Custom Soft! Corneal GP Maria K Walker, OD, MS, FAAO, FSLS! Piggyback Corneal GP Custom Soft BC Doctors of Optometry, Annual Conference 2018! Hybrid! Scleral Hybrid Piggyback Fitting the regular cornea Fitting the irregular cornea THE IRREGULAR CORNEA! Keratoconus! Pellucid Marginal Degeneration! Post-Surgical! RK! LASIK! Post-corneal cross linking! Post-transplant (PKP, LKP)! Post-Infection (HSV, band K)! Other (OSD, dystrophies, trauma etc) Steps of Irregular Corneal Management FITTING CONSIDERATIONS! Step 1: Evaluation of Disease State! Step 2: Selection of lens type! Step 3: Lens Fitting! Step 4: Management of lens fit and disease state! Severity of irregularity: Topography! Patient characteristics! Dexterity! Eye positioning (eyelids, size of socket)! Occupation/Vocation! Personality characteristics & visual sensitivity Scleral lens Conventional GP Specialty GP IRREGULAR CORNEA Surgical design Piggy-back Intralimbal Hybrid Soft CL #%

4 Corneal Topography! Data collected is only useful if accurate! Several factors affect accuracy of image!! Mire quality (tear film)!! Centration!! Eyelids/lashes! Important to evaluate the appropriate display!! Power (Axial vs. Tangential)!! Elevation!! Image Orientation Placido Disc Topography! Small Cone!! Medmont E300, Keratron, Keratron Nova, Keratron Scout, Keratron Piccolo & Magellan! Large Cone!! ReSeeVit, Oculus Keratograph, Atlas 9000!! Oculus Keratograph Medmont E300 Scheimpflug Imaging Poor Topography Good Topography! Oculus Pentacam! Allows for posterior measurements Axial Power Map Elevation Display Map Red = Steep Blue = Flat Measured in D SimK values Red = High Blue = Low Measured in um !%

5 Axial Display Elevation Display on Pentacam Elevation Display The Irregular Cornea! Keratoconus! Pellucid Marginal Degeneration! Post-Surgical! RK! LASIK! Post-corneal cross linking! Post-transplant (PKP, LKP)! Post-Infection (HSV, band K)! Other (OSD, dystrophies, trauma etc) Keratoconus Pellucid marginal degeneration Keratoconus Axial Display Elevation Display &%

6 2/2/18 Keratoconus Soft CL for Keratoconus Spherical and toric Very mild forms Custom lathe-cut soft lens designs Nipple Cone Oval Cone Globus Cone Aberration-control optics Best candidates Nipple and globus-type cones Concentric 360-degree peripheral topography Corneal GP for Keratoconus Apical Clearance Apical Bearing 4

7 Three-Point Touch Piggy-back! Rigid lens fit over top of soft lens! Integrate rigid lens into soft carrier lens! Candidates!! People who cannot tolerate rigid lens!! Poor lens-to-cornea fitting relationship! Traditional piggy-back!! SiHi lens!! Low power (+ or 0.50 D)!! High power (+6.00 D) for stability Disease Progression: Keratoconus Disease Progression: Keratoconus (post CXL) Fitting the Post-CXL Eye -! Wait at least 6 weeks (co-manage with surgeon) -! Considerations -! Post-CXL haze -! Inflammation -! Topographical changes Axial Display Elevation Display (%

8 Axial Display Elevation Display Post-Surgical Flat Meridian Steep Meridian Fitting Goals in Post-Surgical Eyes -! Avoid interacting with incision sites -! Make use of oblate designs -! Consider corneal hypoxia -! Compromised endothelium after surgery Custom Soft Contact Lenses Special post-surgical consideration: OXYGEN! SiHy lens designs available! Radial Keratotomy (RK) Radial Keratotomy (RK)! Slash for Cash! A blade with a fool at both ends! A Russian conspiracy to blind 2 million Americans )%

9 Scarring Iron Deposition HexK Incisions Features of RK!! Complications!! Over correction!! Under correction!! Irregular astigmatism!! Fluctuating vision!! Topography Features!! Central 3-5mm flattening!! Paracentral knee!! Steep periphery Contact Lenses for RK Soft Contact Lenses for RK! Soft CL! Corneal GP lenses!!piggyback! Hybrid lenses! Scleral contact lenses!! Increased risks of neovascularization, edema, and infection!! Use EW lenses for DW only!! Silicone-Hydrogels with high Dk!! Caution with torics!! Unstable!! Flimsy cornea Radial Keratotomy (RK) Oblate Cornea post-pk and RK! Hyperopic Shifts at Altitude (Mader, et. al., 1996)!! RK, PRK, and Controls at Pikes Peak!! 14,100 feet!! Day 1!! ± 0.50 D.!! Day 3!! ± 1.01 D.! Due to Hypoxia (Winkle, et.al., 1998) *%

10 Corneal Transplant Penetrating Keratoplasty Lamellar Keratoplasty Complications of PK! Wound/suture complications!! Breaks and leaks ACUTE! Increased IOP! Endopthalmitis! Transplant rejection CHRONIC! Cataracts! Irregular astigmatism Khoudadoust line Contact Lenses for PK! 60% require contact lenses! Irregular astigmatism! Central corneal flattening Corneal GP lenses: Post transplant! Diameter: mm!! VAULT over graft! Reverse Geometry! Piggyback! caution with Dk Fitting Goal: Avoid interaction with incision sites Bulging Graft Scleral Lenses Post-Transplant 15mm : 5200um Normal SAG: ~3800um = 1400um deeper than normal AC = 1.4mm! $%

11 Scleral Lenses in PKP patients! Retrospective review of 33 patient records! Monitored sclerals over 5 year period! 2 patients d/c lens wear due to lens discomfort! 12 out of 31 (39%) experienced serious graft complications!! Microbial keratitis (2)!! Graft rejection (8 controlled with steroid, 2 re-grafted)! Total failure rate: 19.4% Scleral Lens Fitting Optic Zone (OZ) Transition Zone (TZR) Intermediate Zone (ITZ) Landing Zone (LZR) Fitting the Zones Optic Zone (OZ): Vault Transition Zone (TZR): Vault Intermediate Zone (IZR): Vault Landing Zone (LZR): Land evenly and smoothly Apical Bearing Ideal Clearance: um Intermediate Zone (Limbal) Appropriate Limbal Clearance Too much Inadequate Limbal Clearance Epithelial breakdown +%

12 (Scleral) Landing Zone Well-aligned Scleral Landing Summary of Irregular Cornea CL Fitting! Many classifications:! Main indications: keratoconus (post CXL), PMD, post-rk /LASIK / PKP / LKP)! Not rocket science but should proceed cautiously! Major considerations:! Lens type! Disease state (health of tissues) Questions? Feel free to me with questions: mkwalker@central.uh.edu #,%